As a cardiac electrophysiologist with extensive experience in interpreting electrocardiograms (ECGs), I can explain the significance of the QRS complex. The QRS wave represents the electrical activity of the ventricles as they are depolarized, which is the process that initiates the contraction of the heart muscle. This contraction is essential for pumping blood out of the heart and into the circulatory system. The QRS complex is typically the most prominent part of the ECG waveform and is composed of three phases: the Q wave, the R wave, and the S wave. The Q wave is usually the first negative deflection after the P wave, the R wave is the first positive deflection following the Q wave, and the S wave is the subsequent negative deflection. The morphology and duration of the QRS complex can provide valuable information about the heart's electrical conduction system and can be indicative of various cardiac conditions. read more >>

The QRS complex is a name for the combination of three of the graphical deflections seen on a typical electrocardiogram (EKG or ECG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the right and left ventricles of the human heart.read more >>